Our study explored spatial and temporal distribution of a suite of flame retardants in marine and terrestrial apex predators. The results found geographic variations in flame retardant concentrations in harbor seals (Phoca vitulina) from Gulf of Maine, California, and Sweden. Although PBDEs exhibited clear temporal changes over time, no clear trends were observed between 2000 and 2018. In North American peregrine falcon (Falco peregrinus) eggs, urban influence was observed for selected flame retardants. Compared to marine ecosystems, temporal changes of flame retardants showed a lagging effect in terrestrial ecosystems, requiring more time to monitor the contamination trends.